The invention relates to a rotary knob which can be retracted in a control unit, having a bearing element and an actuating element which can be displaced axially in the bearing element, the bearing element and the actuating element being connected to each other via a spring element for exerting an axial force on the actuating element, and the bearing element having a guideway with two end positions for a latching element, which end positions are essentially arranged axially one behind the other and determine an actuating position and a rest position, offset axially with respect to the actuating position, of the actuating element.
A retractable rotary knob of this type is disclosed, for example, in DE 34 27 378 A1 and in DE 42 30 160 A1.
Retractable rotary knobs are used for adjusting switching or regulating devices arranged behind a switch panel. Retractable rotary knobs of this type are used in particular in domestic appliances, for example ovens or washing machines. In the normal actuating position, the actuating element of the rotary knob protrudes beyond the control unit""s surface, so that rotation of the actuating element enables the desired settings to be carried out. Exerting an axial pressure on the actuating element causes the latter to be pushed into the control unit counter to the force of a spring element. As this happens, a latching element runs through a guideway and latches in an end position which determines the rest position of the actuating element. In the rest position, the actuating element essentially ends at the surface of the control unit. In order to avoid mechanical wear of the latching element against the guideway, in DE 34 27 378 A1 it is proposed to support the latching element in a movable manner and to press it into the guideway by means of a further spring element.
During assembly of the known, retractable rotary knobs, the bearing element, the actuating element, the spring element and the resiliently mounted latching element have to be joined together. The latching element in particular is a small part making its handling difficult during installation. The object of the invention is therefore to specify a retractable rotary knob which has a simplified structure and can be assembled from the component parts in a particularly simple manner.
In the case of a rotary knob of the generic type, the object is achieved by the latching element being integrated in the spring element. This refinement according to the invention of a retractable rotary knob means that the separate insertion of the latching element is therefore no longer applicable. The latching element and the spring element are designed as one part, thereby simplifying the installation. The spring element is, in particular, designed as a coiled spring. In a preferred embodiment, that end of the coiled spring which is connected to the actuating element is bent over in the axial direction into the interior of the coiled spring and subsequently is bent over approximately at right angles with respect to the axis of the spring element, in order to realize the latching element. To connect the spring element to the actuating element in a simple manner, provision is made for the actuating element to have a guide groove into which that end of the coiled spring which acts as the latching element can be introduced in a simple manner.
In addition to the known application in domestic appliances, the rotary knob according to the invention can, in particular, also be used in motor-vehicle control units. To this end, the rotary knob is connected to a rotary regulator, for example. Preferred spheres of application in a motor vehicle are control elements of a motor-vehicle air-conditioning unit and, in particular in this case, a control element for temperature control. Since a control element of this type is not needed continuously, the design as a retractable rotary knob would be especially relevant here. In the rest position, the retractable rotary knob is then protected against damage. At the same time, the control knob also satisfies aesthetic requirements. A further sphere of application in a motor vehicle is the use of the rotary knob as a control element of audio equipment, in particular of a radio.